Inbred corn line LH179

ABSTRACT

An inbred corn line, designated LH179, is disclosed. The invention relates to the seeds of inbred corn line LH179, to the plants of inbred corn line LH179 and to methods for producing a corn plant produced by crossing the inbred line LH179 with itself or another corn line. The invention further relates to hybrid corn seeds and plants produced by crossing the inbred line LH179 with another corn line.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinctive corn inbred line,designated LH179. There are numerous steps in the development of anynovel, desirable plant germplasm. Plant breeding begins with theanalysis and definition of problems and weaknesses of the currentgermplasm, the establishment of program goals, and the definition ofspecific breeding objectives. The next step is selection of germplasmthat possess the traits to meet the program goals. The goal is tocombine in a single variety or hybrid an improved combination ofdesirable traits from the parental germplasm. These important traits mayinclude higher yield, resistance to diseases and insects, better stalksand roots, tolerance to drought and heat, and better agronomic quality.

Choice of breeding or selection methods depends on the mode of plantreproduction, the heritability of the trait(s) being improved, and thetype of cultivar used commercially (e.g., F₁ hybrid cultivar, purelinecultivar, etc.). For highly heritable traits, a choice of superiorindividual plants evaluated at a single location will be effective,whereas for traits with low heritability, selection should be based onmean values obtained from replicated evaluations of families of relatedplants. Popular selection methods commonly include pedigree selection,modified pedigree selection, mass selection, and recurrent selection.

The complexity of inheritance influences choice of the breeding method.Backcross breeding is used to transfer one or a few favorable genes fora highly heritable trait into a desirable cultivar. This approach hasbeen used extensively for breeding disease-resistant cultivars. Variousrecurrent selection techniques are used to improve quantitativelyinherited traits controlled by numerous genes. The use of recurrentselection in self-pollinating crops depends on the ease of pollination,the frequency of successful hybrids from each pollination, and thenumber of hybrid offspring from each successful cross.

Each breeding program should include a periodic, objective evaluation ofthe efficiency of the breeding procedure. Evaluation criteria varydepending on the goal and objectives, but should include gain fromselection per year based on comparisons to an appropriate standard,overall value of the advanced breeding lines, and number of successfulcultivars produced per unit of input (e.g., per year, per dollarexpended, etc.).

Promising advanced breeding lines are thoroughly tested and compared toappropriate standards in environments representative of the commercialtarget area(s) for three years at least. The best lines are candidatesfor new commercial cultivars; those still deficient in a few traits areused as parents to produce new populations for further selection.

These processes, which lead to the final step of marketing anddistribution, usually take from eight to 12 years from the time thefirst cross is made. Therefore, development of new cultivars is atime-consuming process that requires precise forward planning, efficientuse of resources, and a minimum of changes in direction.

A most difficult task is the identification of individuals that aregenetically superior, because for most traits the true genotypic valueis masked by other confounding plant traits or environmental factors.One method of identifying a superior plant is to observe its performancerelative to other experimental plants and to a widely grown standardcultivar. If a single observation is inconclusive, replicatedobservations provide a better estimate of its genetic worth.

The goal of plant breeding is to develop new, unique and superior corninbred lines and hybrids. The breeder initially selects and crosses twoor more parental lines, followed by repeated selfing and selection,producing many new genetic combinations. The breeder can theoreticallygenerate billions of different genetic combinations via crossing,selfing and mutations. The breeder has no direct control at the cellularlevel. Therefore, two breeders will never develop the same line, or evenvery similar lines, having the same corn traits.

Each year, the plant breeder selects the germplasm to advance to thenext generation. This germplasm is grown under unique and differentgeographical, climatic and soil conditions, and further selections arethen made, during and at the end of the growing season. The inbred lineswhich are developed are unpredictable. This unpredictability is becausethe breeder's selection occurs in unique environments, with no controlat the DNA level (using conventional breeding procedures), and withmillions of different possible genetic combinations being generated. Abreeder of ordinary skill in the art cannot predict the final resultinglines he develops, except possibly in a very gross and general fashion.The same breeder cannot produce the same line twice by using the exactsame original parents and the same selection techniques. Thisunpredictability results in the expenditure of large research monies todevelop a superior new corn inbred line.

The development of commercial corn hybrids requires the development ofhomozygous inbred lines, the crossing of these lines, and the evaluationof the crosses. Pedigree breeding and recurrent selection breedingmethods are used to develop inbred lines from breeding populations.Breeding programs combine desirable traits from two or more inbred linesor various broad-based sources into breeding pools from which inbredlines are developed by selfing and selection of desired phenotypes. Thenew inbreds are crossed with other inbred lines and the hybrids fromthese crosses are evaluated to determine which have commercialpotential.

Pedigree breeding is used commonly for the improvement ofself-pollinating crops or inbred lines of cross-pollinating crops. Twoparents which possess favorable, complementary traits are crossed toproduce an F₁. An F₂ population is produced by selfing one or several F₁'s or by intercrossing two F₁ 's (sib mating). Selection of the bestindividuals is usually begun in the F₂ population; then, beginning inthe F₃, the best individuals in the best families are selected.Replicated testing of families, or hybrid combinations involvingindividuals of these families, often follows in the F₄ generation toimprove the effectiveness of selection for traits with low heritability.At an advanced stage of inbreeding (i.e., F₆ and F₇), the best lines ormixtures of phenotypically similar lines are tested for potentialrelease as new cultivars.

Mass and recurrent selections can be used to improve populations ofeither self- or cross-pollinating crops. A genetically variablepopulation of heterozygous individuals is either identified or createdby intercrossing several different parents. The best plants are selectedbased on individual superiority, outstanding progeny, or excellentcombining ability. The selected plants are intercrossed to produce a newpopulation in which further cycles of selection are continued.

Backcross breeding has been used to transfer genes for a simplyinherited, highly heritable trait into a desirable homozygous cultivaror inbred line which is the recurrent parent. The source of the trait tobe transferred is called the donor parent. The resulting plant isexpected to have the attributes of the recurrent parent (e.g., cultivar)and the desirable trait transferred from the donor parent. After theinitial cross, individuals possessing the phenotype of the donor parentare selected and repeatedly crossed (backcrossed) to the recurrentparent. The resulting plant is expected to have the attributes of therecurrent parent (e.g., cultivar) and the desirable trait transferredfrom the donor parent.

Descriptions of other breeding methods that are commonly used fordifferent traits and crops can be found in one of several referencebooks (e.g., Allard, 1960; Simmonds, 1979; Sneep et al., 1979; Fehr,1987).

Proper testing should detect any major faults and establish the level ofsuperiority or improvement over current cultivars. In addition toshowing superior performance, there must be a demand for a new cultivarthat is compatible with industry standards or which creates a newmarket. The introduction of a new cultivar will incur additional coststo the seed producer, the grower, processor and consumer; for specialadvertising and marketing, altered seed and commercial productionpractices, and new product utilization. The testing preceding release ofa new cultivar should take into consideration research and developmentcosts as well as technical superiority of the final cultivar. Forseed-propagated cultivars, it must be feasible to produce seed easilyand economically.

Once the inbreds that give the best hybrid performance have beenidentified, the hybrid seed can be reproduced indefinitely as long asthe homogeneity of the inbred parent is maintained. A single-crosshybrid is produced when two inbred lines are crossed to produce the F₁progeny. A double-cross hybrid is produced from four inbred linescrossed in pairs (A×B and C×D) and then the two F₁ hybrids are crossedagain (A×B)×(C×D). Much of the hybrid vigor exhibited by F₁ hybrids islost in the next generation (F₂). Consequently, seed from hybridvarieties is not used for planting stock.

Corn is an important and valuable field crop. Thus, a continuing goal ofplant breeders is to develop stable, high yielding corn hybrids that areagronomically sound. The reasons for this goal are obviously to maximizethe amount of grain produced on the land used and to supply food forboth animals and humans. To accomplish this goal, the corn breeder mustselect and develop corn plants that have the traits that result insuperior parental lines for producing hybrids.

SUMMARY OF THE INVENTION

According to the invention, there is provided a novel inbred corn line,designated LH179. This invention thus relates to the seeds of inbredcorn line LH179, to the plants of inbred corn line LH179 and to methodsfor producing a corn plant produced by crossing the inbred line LH179with itself or another corn line. This invention further relates tohybrid corn seeds and plants produced by crossing the inbred line LH179with another corn line.

DEFINITIONS

In the description and tables which follow, a number of terms are used.In order to provide a clear and consistent understanding of thespecification and claims, including the scope to be given such terms,the following definitions are provided:

Predicted RM

This trait for a hybrid, predicted relative maturity (RM), is based onthe harvest moisture of the grain. The relative maturity rating is basedon a known set of checks and utilizes conventional maturity systems suchas the Minnesota Relative Maturity Rating System.

MN RM

This represents the Minnesota Relative Maturity Rating (MN RM) for thehybrid and is based on the harvest moisture of the grain relative to astandard set of checks of previously determined MN RM rating. Regressionanalysis is used to compute this rating.

Yield (Bushels/Acre)

The yield in bushels/acre is the actual yield of the grain at harvestadjusted to 15.5% moisture.

Moisture

The moisture is the actual percentage moisture of the grain at harvest.

GDU Silk

The GDU silk (=heat unit silk) is the number of growing degree units(GDU) or heat units required for an inbred line or hybrid to reach silkemergence from the time of planting. Growing degree units are calculatedby the Barger Method, where the heat units for a 24-hour period are:##EQU1## The highest maximum used is 86° F. and the lowest minimum usedis 50° F. For each hybrid, it takes a certain number of GDUs to reachvarious stages of plant development. GDUs are a way of measuring plantmaturity.

Stalk Lodging

This is the percentage of plants that stalk lodge, i.e., stalk breakage,as measured by either natural lodging or pushing the stalks determiningthe percentage of plants that break off below the ear. This is arelative rating of a hybrid to other hybrids for standability.

Root Lodging

The root lodging is the percentage of plants that root lodge; i.e.,those that lean from the vertical axis at an approximate 30° angle orgreater would be counted as root lodged.

Plant Height

This is a measure of the height of the hybrid from the ground to the tipof the tassel, and is measured in centimeters.

Ear Height

The ear height is a measure from the ground to the ear node attachment,and is measured in centimeters.

Dropped Ears

This is a measure of the number of dropped ears per plot, and representsthe percentage of plants that dropped an ear prior to harvest.

DETAILED DESCRIPTION OF THE INVENTION

Inbred corn line LH179 is a yellow dent corn with superiorcharacteristics, and provides an excellent parental line in crosses forproducing first generation (F₁) hybrid corn.

LH179 is a corn inbred line developed from the single cross EX1343×LH85by selfing and using the pedigree system of plant breeding. Yield, stalkquality, root quality, disease tolerance, late plant greenness, lateplant intactness, ear retention, pollen shedding ability, silkingability and corn borer tolerance were the criteria used to determine therows from which ears were selected.

Inbred corn line LH179 has the following morphologic and othercharacteristics (based primarily on data collected at Williamsburg,Iowa).

VARIETY DESCRIPTION INFORMATION

1. TYPE: Dent

2. REGION WHERE DEVELOPED: Northcentral U.S.

3. MATURITY:

    ______________________________________                                                             Days Heat Units                                          ______________________________________                                        From emergence to 50% of plants in silk:                                                             73     1264                                            From emergence to 50% of plants in pollen                                                            73     1264                                            ______________________________________                                         ##STR1##                                                                     -  4. PLANT:                                                              

Plant Height (to tassel tip): 180.6 cm (SD=8.64)

Ear Height (to base of top ear): 53.5 cm (8.03)

Average Length of Top Ear Internode: 13.3 cm (1.53)

Average number of Tillers: 0 (0)

Average Number of Ears per Stalk: 1.0 (0.0)

Anthocyanin of Brace Roots: Absent

5. LEAF:

Width of Ear Node Leaf 9.7 cm (0.72)

Length of Ear Node Leaf: 73.2 cm (3.32)

Number of leaves above top ear: 5 (0.42)

Leaf Angle from 2nd Leaf above ear at anthesis to Stalk above leaf: 25°(4.79)

Leaf Color: Dark Green--Munsell Code 5 GY 3/4

Leaf Sheath Pubescene (Rate on scale from 1=none to 9=like peach fuzz):5

Marginal Waves (Rate on scale from 1=none to 9=many): 2

Longitudinal Creases (Rate on scale from 1=none to 9=many): 2

6.TASSEL:

Number of Lateral Branches: 7 (1.27)

Branch Angle from Central Spike: 36 (10.30)

Tassel Length (from top leaf collar to tassel top): 43.7 cm (4.15)

Pollen Shed (Rate on scale from 0=male sterile to 9=heavy shed): 7

Anther Color: Yellow--Munsell Code 2.5Y 8/6

Glume Color: Medium Green--Munsell Code 5GY 5/6

Bar Glumes: Absent

7a. EAR: (Unhusked Data)

Silk Color (3 days after emergency): Light Green--Munsell Code 2.5GY 8/6

Fresh Husk Color (25 days after 50% silking): Medium Green--Munsell Code2.5GY 7/6

Dry Husk Color (65 days after 50% silking): Buff--Munsell Code 7.5YR 7/4

Position of Ear: Upright

Husk Tightness (Rate on scale from 1=very loose to 9=very tight): 3

Husk Extension: Medium (<8 cm)

7b. EAR: (Husked Ear Data)

Ear Length: 13.3 cm (1.53)

Ear Diameter at mid-point: 39.0 mm (2.0)

Ear Weight: 72.2 gm (19.49)

Number of Kernel Rows: 12 (1.23)

Kernel Rows: Distinct

Row Alignment: Straight

Shank Length: 11.9 cm (2.72)

Ear Taper: Average

8. KERNEL: (Dried)

Kernel Length: 11.6 mm (0.94)

Kernel Width: 9.7 mm (0.67)

Kernel Thickness: 5.0 mm (0.81)

Round Kernels (Shape Grade): 78.0% (4.50)

Aleurone Color Pattern: Homozygous

Aleurone Color: White

Hard Endosperm Color: Yellow--Munsell code 2.5Y 6/8

Endosperm Type: Normal Starch

Weight per 100 kernels (unsized sample): 25.2 gm (0.54)

9. COB:

Cob Diameter at Mid-Point: 28.1 mm (2.4)

Cob Color: Light Red--Munsell code 5R 5/6

10. DISEASE RESISTANCE:

Rating 1=(most susceptible) through 9=(most resistant)!

3 Eyespot (Kabatiella zeae)

2 Gray Leaf Spot (Cercospora zeae-maydis)

5 Northern Leaf Blight (Exserohilum turcicum) race 2

3 Southern Leaf Blight (Bipolaris maydis)

9 Northern Leaf Spot Race 3 (H. Carbonum)

11. AGRONOMIC TRAITS:

4 Stay Green (at 65 days after anthesis) (Rate on scale from 1=worst to9=excellent)

0% Dropped Ears (at 65 days after anthesis)

0% Pre-anthesis Brittle Snapping

0% Pre-anthesis Root Lodging

0% Post-anthesis Root Lodging (at 65 days after anthesis)

This invention is also directed to methods for producing a corn plant bycrossing a first parent corn plant with a second parent corn plant,wherein the first or second corn plant is the inbred corn plant from theline LH179. Further, both first and second parent corn plants may befrom the inbred line LH179. Therefore, any methods using the inbred cornline LH179 are part of this invention: selfing, backcrosses, hybridbreeding, and crosses to populations. Any plants produced using inbredcorn line LH179 as a parent are within the scope of this invention.Advantageously, the inbred corn line is used in crosses with other cornvarieties to produce first generation (F₁) corn hybrid seed and plantswith superior characteristics.

As used herein, the term "plant" includes plant cells, plantprotoplasts, plant cell of tissue culture from which corn plants can beregenerated, plant calli, plant clumps, and plant cells that are intactin plants or parts of plants, such as pollen, flowers, kernels, ears,cobs, leaves, husks, stalks, and the like.

Tissue culture of corn is described in European Patent Application,Publication No. 160,390, incorporated herein by reference. Corn tissueculture procedures are also described in Green and Rhodes, "PlantRegeneration in Tissue Culture of Maize", Maize for Biological Research(Plant Molecular Biology Association, Charlottesville, Va. 1982), at367-372. Thus, another aspect of this invention is to provide for cellswhich upon growth and differentiation produce the inbred line LH179.

EX1343 and LH85, the progenitors of LH179, are proprietary field corninbred lines of Holden's Foundation Seeds, Inc. of Williamsburg, Iowa.

LH179 is most similar to LH85. However, the most distinguishingdifference is the tassel. The attitude of the main stem and lateralbranches of the LH179 tassel are not erect and are perpendicular to theplant. The attitude of the main stem and lateral branches of the LH85tassel are erect and upright. The tassel of LH179 is not wrapped in theflag leaf and does not "buggywhip") as the tassel is unencumbered andfully exposed. This trait exhibited by LH179 is also not the result ofherbicide or other agricultural chemical damage. This trait has beenobserved at several locations and this phenotypic trait has beenconsistently expressed. LH179 is darker green in plant color than LH85.When using the Munsell color charts for Plant Tissues as a reference,LH179 would be classified as 5GY 3/4 and LH82 would be classified as 5GY4/4.

LH179 is an early season field corn inbred line that flowers slightlyearlier than LH163. LH179 is a very good pollinator and may havepotential use as a seed parent in the northern corn belt. Hybridscontaining LH179 have a medium girthy ear and display excellent lateseason plant appearance.

Some of the criteria used to select ears in various generations include:yield, stalk quality, root quality, disease tolerance, late plantgreenness, late season plant intactness, ear retention, pollen sheddingability, silking ability, and corn borer tolerance. During thedevelopment of the line, crosses were made to inbred testers for thepurpose of estimating the line's general and specific combining ability,and evaluations were run by the Williamsburg, Iowa Research Station. Theinbred was evaluated further as a line and in numerous crosses by theWilliamsburg and other research stations across the Corn Belt. Theinbred has proven to have a very good combining ability in hybridcombinations.

The inbred has shown uniformity and stability for all traits. It hasbeen self-pollinated and ear-rowed a sufficient number of generations,with careful attention to uniformity of plant type to ensurehomozygosity and phenotypic stability. The line has been increased bothby hand and sibbed in isolated fields with continued observations foruniformity. No variant traits have been observed or are expected inLH179.

TABLES

In the tables that follow, the traits and characteristics of inbred cornline LH179 are given in hybrid combination. The data collected on inbredcorn line LH179 is presented for the key characteristics and traits. Thetables present yield test information about LH179. LH179 was tested inseveral hybrid combinations at numerous locations, with two or threereplications per location. Information about these hybrids, as comparedto several check hybrids, is presented.

The first pedigree listed in the comparison group is the hybridcontaining LH179. Information for the pedigree includes:

1. Mean yield of the hybrid across all locations.

2. A mean for the percentage moisture (% M) for the hybrid across alllocations.

3. A mean of the yield divided by the percentage moisture (Y/M) for thehybrid across all locations.

4. A mean of the percentage of plants with stalk lodging (% Stalk)across all locations.

5. A mean of the percentage of plants with root lodging (% Root) acrossall locations.

6. A mean of the percentage of plants with dropped ears (% Drop).

7. The number of locations indicates the locations where these hybridswere tested together.

The series of hybrids listed under the hybrid containing LH179 areconsidered check hybrids. The check hybrids are compared to hybridscontaining the inbred LH179.

The (+) or (-) sign in front of each number in each of the columnsindicates how the mean values across plots of the hybrid containinginbred LH179 compare to the check crosses. A (+) or (-) sign in front ofthe number indicates that the mean of the hybrid containing inbred LH179was greater or lesser, respectively, than the mean of the check hybrid.For example, a +4 in yield signifies that the hybrid containing inbredLH179 produced 4 bushels more corn than the check hybrid. If the valueof the stalks has a (-) in front of the number 2, for example, then thehybrid containing the inbred LH179 had 2% less stalk lodging than thecheck hybrid.

                  TABLE 1                                                         ______________________________________                                        OVERALL COMPARISONS                                                           LH74 × LH179 HYBRID VERSUS CHECK HYBRIDS                                            Mean                 %    %     %                                 Pedigree    Yield   % M    Y/M   Stalk                                                                              Root  Drop                              ______________________________________                                        LH179 × LH74                                                                        151     18.11  8.33  7    1     1                                 (at 13 Loc's)                                                                 As Compared To:                                                               LH202 × LH163                                                                       -4      -2.02  +.63  +3   0     0                                 LH74 × LH163                                                                        -6      -1.54  +.37  +3   0     0                                 LH74 × LH85                                                                         -2      -0.63  +.19  +1   +1    0                                 LH146 × LH172                                                                       +1      -0.43  +.24  0    0     0                                 Pioneer 3751                                                                              -7      +.31   -0.51 -1   +1    0                                 A632 × LH163                                                                        +8      +.60   +.17  +2   -1    0                                 ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        OVERALL COMPARISONS                                                           LH202 × LH179 HYBRID VERSUS CHECK HYBRIDS                                           Mean                 %    %     %                                 Pedigree    Yield   % M    Y/M   Stalk                                                                              Root  Drop                              ______________________________________                                        LH179 × LH202                                                                       152     18.91  8.03  4    0     0                                 (at 15 Loc's)                                                                 As Compared To:                                                               Pioneer 3751                                                                              0       +.35   -0.15 -5   0     0                                 LH146 × LH82                                                                        +10     +.73   +.21  -9   -1    0                                 LH168 × LH146                                                                       +1      +1.21  -0.52 0    0     -1                                ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                        OVERALL COMPARISONS                                                           LH179 × LH223 HYBRID VERSUS CHECK HYBRIDS                                           Mean                 %    %     %                                 Pedigree    Yield   % M    Y/M   Stalk                                                                              Root  Drop                              ______________________________________                                        LH179 × LH223                                                                       137     17.90  7.68  6    0     0                                 (at 9 Loc's)                                                                  As Compared To:                                                               LH223 × LH85                                                                        +5      -0.64  +.54  -4   0     0                                 LH145 × A641)                                                                       +16     -0.18  +.95  -3   0     0                                 (LH164                                                                        LH145 × A641)                                                                       +8      -0.04  +.45  -2   0     0                                 (LH85                                                                         LH223 × LH160                                                                       +10     -0.04  +.58  -1   -1    0                                 LH85 × LH145                                                                        0       +.04   -0.02 -4   0     0                                 LH145 × A641)                                                                       +29     +1.43  +1.08 -2   -1    0                                 (LH162                                                                        ______________________________________                                    

DEPOSIT INFORMATION

Inbred seeds of LH179 have been placed on deposit with the American TypeCulture Collection (ATCC), Rockville, Md. 20852, under Deposit AccessionNumber 97743 on Sep. 26, 1996. A Plant Variety Protection Certificate isbeing applied for with the United States Department of Agriculture.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity andunderstanding, it will be obvious that certain changes and modificationsmay be practiced within the scope of the invention, as limited only bythe scope of the appended claims.

What is claimed is:
 1. Inbred corn seed designated LH179 having ATCCaccession No.
 97743. 2. A corn plant produced by growing the seed ofclaim
 1. 3. Pollen of the plant of claim
 2. 4. An ovule of the plant ofclaim
 2. 5. An inbred corn plant capable of expressing all thephysiological and morphological characteristics of the corn plant ofclaim
 2. 6. A tissue culture comprising regenerable cells of the plantof claim
 2. 7. A corn plant regenerated from said tissue culture ofclaim 6, wherein said corn plant is capable of expressing all thephysiological and morphological characteristics of the corn plant ofclaim
 2. 8. A method to produce a hybrid corn seed comprising the stepsof:a) planting in pollinating proximity seeds of corn inbred line LH179having ATCC No. 97743 and another inbred line; b) cultivating cornplants resulting from said seeds until said plants bear flowers; c)emasculating the male flowers of the plants of either inbred line; d)allowing cross pollination to occur between said inbred lines; and, e)harvesting seeds produced on said emasculated plants of the inbred line.9. A first generation (F₁) hybrid corn plant produced by growing saidhybrid corn seed of claim
 8. 10. Seed derived from the hybrid corn plantof claim 9.